Electro-magnetic attenuator



April 29, 1953 E. E. REYNOLDS ELECTRO-MAGNETIC ATTENUATOR Filed July 30,1956 mvsmozz E /mer E. Reyna/d3 United States Patent ELECTRD-MAGNETICATTENUATOR Elmer E. Reynolds, Glendale, Calif. Application July so,1956, Serial No. 600,873

4 Claims. c1. 179-1 This invention relates to electro-magneticattenuators for sound distribution.

It is an object of the present invention to provide an electro-magneticattenuator for sound distribution which will create an effect reducingthe listener's ability to locate the sound source and thereby add aspace illusion.

It is another object of the present invention to provide anelectro-magnetic attenuator of the above type which will improveacoustical quality in most applications and wherein several speakers areused in a given area and attenuated by the present invention.

Other objects of the invention are to provide an electromagneticattenuator bearing the above objects in mind which is of simpleconstruction, has a minimum number of parts, is inexpensive tomanufacture and effective in use.

For other objects and for a better understanding of the invention,reference may be had to the following detailed description taken inconnection with the accompanying drawing, in which:

Figure 1 is a top plan view shown partly schematically and Fig. 2 is aside elevational view thereof taken along the line 2-2 of Fig. 1 andshown partly schematically.

Referring now more in detail to the drawings, represents an O-ring whichis supported on the idler pulleys 11 and 12 and which is driven by thefriction drive pulley 13, the pulleys 11 and 12 being mounted on theshafts 14 and 15 respectively, while the drive pulley 13 is mounted onthe shaft 16.

Four equi-angularly spaced coils 17 surround the O- ring 10, one end ofeach of the coils 17 being connected to one terminal of the speakerindicated generally at 18 while the other end of each of the coils 17 isconnected to the negative terminal of the amplifier, not shown, as at19. The other terminal of each of the speakers 18 is connected to thepositive terminal of the amplifier by the conductor 20, as at 21. Thus,four coils 17 are provided, each having their own speaker 18 andamplifier. The circuits of each of the coils are identical.

A portion of the O-ring 10 is made up of an iron slug 22 adapted to movethrough the coil 17 of each of the circuits upon rotation of the drivepulley 13.

The O-ring 10 is formed of a dielectric material.

Thus, the O-ring 10 rotates through the helix type coil 2,832,829Patented Apr. 29, 1958 17 and is supported and driven by the pulleys 11,12 and 13. The speaker attenuation is attained as the iron slug passesthrough the center of the respective coils 17. One attenuating coil iswired in series with each speaker 18 and the cycling of the speakerattenuation is chosen as required. Coil impedance is chosen inaccordance with the amplifier and speakers used in order to attainmaximum efiiciency. The combination or number of speakers used will bedetermined by each application and the invention will not be limited tothe exact number of coils and speakers shown in the drawing, as will bereadily apparent to those skilled in the art. It will also be noted thatthe attenuator may be gear driven externally or internally, as desired,without departing from the spirit and scope of the invention.

It will be noted that one lead from each of the coils goes to thespeaker and the other to the amplifier output. It will also be notedthat the speakers are wired in parallel.

The iron slug 22 may be of various lengths in order to attenuate morethan one speaker simultaneously, if the application requires such.

While various changes may be made in the detail, construction, it shallbe understood that such changes shall be within the spirit and scope ofthe present invention as defined by the appended claims.

What I claim as new and desire to protect by Letters Patent of theUnited States is:

1. An electro-magnetic attenuator for sound distribution comprising anO-ring of dielectric material, a segment of said ring being cut away, anarcuate iron body mounted within the cut away portion of said O-ring,means rotatably mounting said O-ring for rotational movement about itscenter, means for driving said O-ring, a plurality of angularly spacedseparable coils surrounding said O-ring and receiving the sametherethrough, a loud speaker for each of said coils, one terminal ofsaid loud speaker being connected to one end of said coils, the otherterminal of said speaker being connected to the negative terminal of anamplifier, the other end of each of said coils being connected to thepositive terminal of said amplifier whereby to selectively attenuatesaid speakers as said iron slug moves within its respective coil uponrotation of said O-ring.

2. An electro-magnetic attenuator according to claim 1, said means formounting said dielectric O-ring comprising a pair of supporting idlerpllleys bearing on the bottom of said O-ring at opposite sides thereof.

3. An electro-magnetic attenuator according to claim 2, said means fordriving said O-ring comprising a friction pulley bearing on theperiphery of said O-ring at the top thereof intermediate said coils, andmeans for driving said friction pulley.

4. An electro-magnetic attenuator according to claim 1, four coilsequi-spaced being provided, each connected in series with its respectiveamplifier and loud speaker, said speakers being connected in parallelwith each other.

No references cited.

